Roller bit structure



ROLLER BIT STRUCTURE Filed Jan. 23, 1937 3 Sheets-Sheet l INVENTOR 9 a g Roland R.Crurn ATTO R N E! Jan. 17,- 1939, R. R. CRUM ROLLER BIT STRUCTURE Filed Jan. 25, 1937 3 Sheets-Sheet 2 INVENTOR Roi d R. Crum jigwm ATTORNEY Jan. 17', 1939. R R. CRUM ROLLER BIT STRUCTURE Filed Jan. 25, 1937 5 Sheets-Sheet 5 INVENTOR BY ALMA) ATTQFENEY Patented Jan. 17, 1939 UNITED STATES PATENT OFFICE 12 Claims.

This invention relates to a roller bit structure adapted to bore a cylindrical well in the earth.

Bit structures of this general character, incorporating toothed roller discs, are described and claimed in prior patents, issued in the name of Roland R. Crum. One of these patents is entitled: Roller bit bearing structure, issued November 1'7, 1936, and having Number 2,061,141 another is entitled: Structure for roller bits, issued November 24, 1936, and having Number 2,061,933. The general structure is also shown in a copending application, filed in the name of Roland R, Crum on March 14, 1934, under Serial No. 715,504, and entitled: Roller bit.

It is one of the objects of the present invention to provide other forms of the structures 11- lustrated in these prior patents and in the prior application.

In the process of drilling with such roller bits,

it is common to use inside and outside cutters; the,

inside cutters are located closer to the axis of bit rotation, and the outside cutters are so placed that they contact the bottom of the bore hole on an annular surface extending beyond the area contacted by the inside'cutters; and the outside cutters also contact the side of the bore.

The cutters, which are rotatably supported on the bit frame, are rotated from the top of the bore by any appropriate rotary drilling apparatus. These cutters must sustain considerable compression stresses; and the shafts or pins upon which they are mounted must sustain a considerable bending stress, and yet without any substantial resistance to the free rolling of the discs upon them. It is therefore another object of the invention to make it possible to support all the cutters and their shafts or pins in a rigid manner. Care in this regard must be especially exercised in supporting the outer cutters, which are rotatable about axes oblique to the axis of rotation, and usually about pivot pins supported at one end only,

This invention possesses many other advantages, and has other objects which may be made more easily apparent from a consideration of several embodiments of the invention. For this purpose, there are shown a few forms in the drawings accompanying and forming part of the present specification. These forms will now be described in detail, illustrating the general principles of the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

Figure l is a side elevation of a bit structure embodying the invention;

Fig. 2 is a sectional view taken along plane 5 2-2 of Fig. 1;

Fig. 3 is a sectional view taken along plane 33 of Fig. 1;

Fig. 4 is a sectional view taken along plane 4-4 of Fig. 3;

Fig. 5 is a fragmentary view of the bit frame prior to the attaching of the arms for supporting the cross shaft upon which rotary cutters are supported;

Fig. 6 is a plan view of one of the arms adapted to be attached to the bit frame;

Fig. 7 is aside elevation of the arm shown in Fig. 6;

Fig. 8 is a plan of one of the arms that provides a supporting pin on an oblique axis for the 20 outer rotary cutter;

Fig. 9 is an elevation of the arm shown in ig.

Fig. 10 is a view partly in longitudinal section of a modified form of the bit structure;

Fig. 11 is a fragmentary longitudinal sectional view similar to Figure 4, but of a further modified form of the invention;

Fig. 12 is a view taken along plane l2-l2 of a member adapted to cooperate with the oblique 30 outer cutter structure; and a Fig. 13 is a fragmentary longitudinal sectional view also similar to Fig. 4, showing another modified form of the invention.

The bit frame I (Figs. 1-, 2, 3 and 4) is shown 35 as provided with appropriate means for attachment to a drill string; for example, such as the tapered external threaded portion 2. The frame I has a longitudinal axis 3 about which it is rotated, as by the aid of appropriate rotary mecha- 40 nism at the top of the bore. The frame I may furthermore be provided with a longitudinal center aperture for the circulation of mud fluid or the like through the drill string.

In order to operate upon the bottom of the bore 45 in which the bit structure is rotated, there are provided the rotary inner cutters 5 and 6. These cutters are adapted to be rotated about 9. diametric transverse axis 1 intersecting the longitudinal axis 3. In the present instance, they are 50 each shown as being provided with a series of axially spaced sets of teeth indicated at 8, 9, l0,

' ll, 12' and I3 in Fig. 3. These sets of teeth, if desired, are so arranged that the zones operated upon by the teeth of cutter 5 overlap the zones operated upon by the teeth of cutter 6. This fea- '29 as by welding indicated at 38 and 3I.

ture has been explained and described in the prior application hereinbefore referred to.

The manner in which the cutters 5 and 6 are supported will now be described.

For this purpose a stationary transverse shaft I4 is provided, arranged concentrically with the axis of the cutter rotation I. This shaft I4 is so arranged that it provides one or more inner ball races for the ball bearings I5, I6, I I and I8. Thus, for example, the central portion I9 of shaft I4 is of larger diameter than the adjacent portions and 2|. In this way the shoulders 22 and 23 are formed, which cooperate respectively with portions 28 and 2|, forming inner races for the ball bearings I6 and H, to take the end thrust of the bearings. Furthermore, the extremities of shaft I4 are made still smaller in diameter than portions 28 and 2| to form annular shoulders 24 and 25. These shoulders are adapted and 27 formed integrally respectively with the supporting arms 28 and 29. The shoulders 24 and cooperate with the reduced portions 20 and 2| which provide inner ball races respectively for the ball bearings I 5 and I8, to take the end thrust of the bearings. The shaft I4 may be permanently attached to the supporting arms 28 and This may be accomplished by providing a tapered counter-sink to the radial apertures provided through the bosses 26 and 21. The tapered spaces between the ends of shaft I4 and these countersinks can provide a pocket for the deposited welded on metal.

The outer ball races for the ball bearing structures I5, I6, I! and I8 are formed by the aid of appropriate grooves on the inside of the rotary cutters 5 and 6. As shown in the present instance, the inner edges of these rotary cutters may approach close together, so that there is no appreciable center core formed during the process of drilling.

In order further to provide an adequate and strong rotary support for each of the roller cutters 5 and 6, roller bearings 32 are interposed between the exterior cylindrical surface of boss 26 and an internal groove 34 provided in the cutter 5. Similarly, roller bearings 33 are interposed between the exterior cylindrical surface of boss 21 and an internal groove 35 provided in the cutter 6.-

The manner in which the rotary cutters 5 and 6 may be assembled with respect to the shaft I4 and arms 28 and 29 is apparent. The various rolling bearings such as 82, i5 and I6 may be placed in their respective internal grooves in the cutter 5,1;hen the cutter may be placed over the shaft I4 from the outer end of shaft I4 toward the central axis 3. After both of the cutter structures 5 and 6 are thus placed upon the shaft I4, the ends of the shaft may be inserted in the apertures in bosses 26 and 21. Then the shaft I4 may be permanently joined to the arms 28 and 29.

It is apparent that an adequate rigid support is thus provided for the various rotary bearing structures of the cutters 5 and 5. It is also apparent that arms 28 and 29 may first be assembled with the shaft I4 and cutters 5 and 6 as just described, before these arms 28 and 29 are joined to the bit frame i.

For this reason, the arms 28 and 29 are formed as separate pieces adapted to be later permanent- 1y attached as by Welding to the frame I. The individual arm 28 is shown in Figures 6 and 7.

Since arm 28 is identical with arm 29, but one of these arms need be described in detail.

As shown in Figs. 1, 2, 6 and '7, the arm 29 is provided with a pair of side wings 36 and 31 to lend strength and rigidity to the arm. The upper surface 38 (Figure 3) of the arm 29 is shown in this instance as fiat, and as projecting beyond the outer cylindrical surface 39 of the bit frame I. The shoulder formed between the fiat surface 38 and the cylindrical surface 39 provides a pocket'for added welded on metal 40, which extends as an annular band around the cylindrical surface 39 and which serves to attach the arms 28 and 29 to the bottom of the bit frame I. These arms 28 and 29 may each be additionally maintained in accurate position prior to the welding operation as by the aid of a dowel pin M or 42. These dowel pins. extend across the contacting surfaces between the bottom of the frame I and r the arms 28 and 29. to engage the annular end surfaces of bosses 26 The wings 36 and 31 of each of the arms are provided with end portions 43 and 44. These ends are adapted to contact with the square edges of the arms 45 and 48 (Fig. 2). and 46 described hereinafter are provided for supporting outer cutter structures.

To facilitate accurate positioning of the arms 28 and 29 along the longitudinal axis 3 of the bit structure, there is provided a boss 41 on the top of each of these arms and extending transversely across it. This boss may be'machined off by a cut and try method until accurate alinement is accomplished. Welded on metal 48 can then be deposited to attach the surfaces firmly together.

The cutters 5 and 6 operate on the inner zones of the bore. The outer zone is cut by the aid of a pair of rotary outer cutters 48 and 49 (Fig. 4). These cutters may also be provided with a series of teeth and are arranged on axes 58 and 5! which are oblique to the longitudinal axis 3 and intersect this axis at a common point. The cutters 48 and 49 are rotatably supported respectively on the arms 45 and 46. Each of these arms may be provided with an integral pin 52. Since the structure of each of the cutters is identical, a description of the cutter structure utilized in relation with one of the cutters will serve as a description of both structures.

The pin 52 in the form shown in Fig. 4 is provided with a tapered base portion 53 and a threaded end 54. A member 55 forming the inner race for the ball bearings 56 is telescoped over the tapered portion 53. The outer race for these ball bearings is provided by grooves formed in the inside of cutter 48.

The race member 55 has an edge or face contacting with the annular surface provided on arm 45 and surrounding the base of the tapered portion 53. The opposite edge or face 51 of race 55 can provide an annular surface restraining axial movement of the rollers 58. These rollers are interposed as an additional bearing structure between the pin 52 and the roller 48. A counterbore is provided in the cutter 48 to form the outer race for the rollers 58. The inner race for the rollers 58 is formed by the cylindrical surface of a boss 59 which is internally threaded to engage the threaded end 54. The boss 59 is formed integrally with a member 68, forming a head serving to restrain axial movement of rollers 58. It is apparent that by turning the head 88 onto the threads 54 the rotary cutter 48 can be adequately held in place against removal from the pin 52.

It is of the utmost importance to lend rigidity to These arms 45 the oblique cutter structures 48 and 49. For this 76 shown as supported by a welded on arm 95 havingpurpose, as shown most clearly in Figs. 3, 4 and 12, both of these members 68 are provided with an extension 6 I, adapted to contact. at the center of this bit frame I and over the central portions of the cutters 5 and 6. At this place, these extensions 6| may be securely welded together, as indicated at 62. The adjacent faces of these extensions 6| may be beveled as indicated at 63 (Fig. 12), to accommodate the added welded on metal. Thus, a bridge structure is formed between the two cutters 48 and 48 and over the intervening inside cutters 5 and 6.

The arms 45 and 46 are also firmly attached as by welding to the frame I. The added welded on metal portions are indicated at 64 in Figs. 1 and 4. These arms 45 and 46 may be disposed to form extensions of the ribs 65, formed integrally with the frame I. These ribs 65 may have the beveled surface 66 to form one boundary wall for the welded on metal 64. This is clearly indicated in Figure 5. The arm 45 is also shown separate from the bit structure in Figs. 8 and 9. The surface 61 of the arm 45 forms another boundary for the welded on metal 64. As clearly shown in Figure 4, this welded on metal forms a continuous layer from the inside to the outside of the arms 45 and 46.

The outer cutter structures may be supported in other ways than that described. For example, in Fig. 11, the cutter 48 is shown, in which the welded on arm 12 is provided with a slightly different form of pin 13. In this case, the pin 13 has an internal thread M. The member I5 corresponding to member 68 in the form described,

simply telescopes over the outer cylindrical surface of the pin 13, and forms as before, the inner race for the rollers 58. The member 15 is held in place by the aid of a threaded screw 16 passing through an appropriate aperture in the member 15 and engaging the internal threads 14. As before, extensions 6| are provided to form the intervening bridge structure between the members 15.

In the form shown in Fig. 10, the arm 11 supporting the outside cutter 18 is formed with an integral pin 19 that is straight throughout its length, and has an internal thread 88. In this form, the roller bearings 8| are adjacent the base of the pin 18; and the ball bearings 82 are adjacent the free end of the pin 18. The inner race for the rollers 8| is formed by the cylindrical out er surface of a flanged member 83 which rests against the annular surface adjacent the base of the pin 18. The member 83 also forms a portion of the inner race for the balls 82. The other portion of the inner race isformed on the inner end of the member 84 which telescopes over the pin 18. The outer races for both the rollers 8| and the balls 82 are formed by appropriately positioned grooves in the inner surface of the cutter 18. As in the form shown in Fig. 11, the member 84 may be held in place to restrict axial motion of the cutter 18 on pin 18, by the aid of a threaded screw 85 engaging the internal threads 88.

In this form of the invention, extensions 86 are formed on each of the members 84, extending over the cutters 5 and6 to form a bridge construction. They are welded together as indicated at 81. In order to provide further rigidity, a longitudinal leg 88 may be welded over the tops of the extensions 86 and to the bottom of the bit frame 88. The central aperture 80 in the bit frame 88 may be branched as indicated at 8| and 82, in order to provide a central anchoring member 88 for a member 88.

In the form shown in Fig. 13, the cutter 84 is a pin 86 with a tapered base portion 81 and a threaded end 88, as in the first described form. However, the roller bearings 88 are supported adjacent the base of the pin by a race I80, which member also forms a part of the inner race for the balls l0l. race is formed on the inner end of member I02.

Member I02 is adapted to be threaded onto pin 86 to hold the parts in assembled relationship and is provided with a projecting arm I03 adapted- The other part of the inner ball a shaft rigidly supported by the arms, and having an axis passing through the frame axis, said shaft having a pair of portions, spaced on opposite sides of the frame axis, which are of reduced diameter, forming a shoulder at each end of each reduced portion, to form a ball bearing race, a pair of rotary cutters disposed over the shaft and each having a pair of ball races, and ball bearings in the races interposed between the cutters and the shoulders. I

2, In a roller bit structure, a bit frame adapted to be rotated about a longitudinal axis, a pair of oppositely disposed arms supported by the frame, a shaft rigidly supported by the arms, and having an axis passing through the frame axis, and a pair of rotary cutters supported on the shaft, said frame having a surface of contact with each arm, each of said arms having reinforcing wings,

said wings and the arm being secured to the frame. v

3. In a bit structure, a bit frame adapted to be rotated about a longitudinal axis, a pair of oppositely disposed arms, pins respectively rigidly connected to the arms, a pair of rotary cutters respectively rotatably supported by the pins, and

-a pair of means, cooperating respectively with the pins, for retaining said cutters on said pins, each of said pair of means having a member, the members on both of said means being adapted to be joined together to provide a brace for the structure.

4. In a bit structure, a bit frame adapted to.

be rotated about a longitudinal axis, a pair of oppositely disposed arms, pins respectively rigidly connected to the arms, a pair of rotary cutters respectively rotatably supported by the pins, a. pair of means, cooperating respectively with the pins, for retaining said cutters onsaid pins, each of said pair of means having a member, the mem.- bers on both of said means being adapted to be joined together to provide a brace for the struc ture, and a cutter structure rotatably supported on an axis transverse to the axis of the frame, and extending underneath said members and between the rotary cutters.

5. In a bit structure, a bit frame adapted to be rotatedabout a longitudinal axis, a pair of oppositely disposed arms, pins respectively rigidly connected to the arms, a pair of rotary cutters respectively rotatably supported by the pins, and a pair of means, cooperating respectively with the pins, for retaining said cutters on said pins, each of said pair of means having a member, the members on both of said means being adapted to be joined together, as well as to the bottom of the bit frame.

6. In a roller bit structure, a bit frame adapted to be rotated about a longitudinal axis, a pair of oppositely disposed arms, supported by the frame; a shaft rigidly supported by the arms, and having an axis passing through the frame axis, said shaft having a pair of portions, spaced on opposite sides of the frame axis, which are of reduced diameter, forming a shoulder at each end of each reduced portion, to form a ball bearing race, a pair of rotary cutters disposed over the shaft and each having a pair of ball races, ball bearings in the races interposed between the cutters and the shoulders, each of the rotary cutters also forming an outer roller race, axially spaced from the ball races and toward the arms, a

and rollers disposed in said race.

7. In a roller cutter structure, an arm having a supporting pin, a roller cutter disposed over the pin, a rolling bearing structure between the pin and the cutter, means cooperating with the pin to retain the cutter thereon, and a member joined to said means and adapted to be joined upon assembly, with a corresponding member to form a bridge construction.

8. In a roller cutter structure, an arm having a supporting pin, said pin having a threaded end, a roller cutter disposed over the pin, a rolling bearing structure between the pin and the cutter, means threaded on the pin, forming at least one of the races for the bearing structure, and a member joined to said means and adapted to be joined upon assembly, with a corresponding memberto form a bridge construction.

9. In a roller cutter structure, an arm having a supporting pin, said pin having 'an internally threaded end, a roller cutter disposed over the pin, a roller bearing structure between the pin and the cutter, means telescoping over the pin, forming atleast one of the races for the bearing structure, a fastening means passing through the telescoping means and engaging the internal threads in the pin, and a member joined to the telescoping means and adapted to be joined, upon assembly, with a corresponding member to form a bridge structure.

10. In a roller bit structure, a bit frame adapted to be rotated about a longitudinal axis, a rotary cutter structure disposed on an axis diametrically arranged with respect to the longitudinal axis, a pair'of rotary cutter structures, respectively disposed on opposite axes oblique with respect to the longitudinal axis, and a bridge structure joining those cutter structures which are on oblique axes, and disposed over the diametrical rotary cutter structure. I

11. In a roller bit structure, a bit frame adapted to be rotated about a longitudinal axis, a rotary cutter structure disposed on an axis diametrically arranged with respect to the longitudinal axis, a. pair of rotary cutter structures, respectively disposed on opposite axes oblique with respect to the longitudinal axis, and a bridge structure joining those cutter structures which are on-oblique axes, and disposed over the diametrical rotary cutter structure, and joined to the bottom of the bit frame.

12. In a roller bit structure, a rotary bit frame, a pair of oppositely disposed arms supported by the frame, a shaft supported by the arms, and having an axis transverse to the frame, said shaft having an intermediate part and portions of reduced diameter respectively at opposite ends of said intermediate part and each portion forming a shoulder adjacent said intermediate portion, said shoulder providing a ball race, a pair of rotary cutters disposed over the shaft and each having a ball race cooperating respectively with said shoulders, and ball bearings interposed between the cutters and the shoulders.

' ROLAND R. CRUM. 

